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SHD digital attenuation can reduce bit depth? 5 months 1 week ago #54342

  • Logix1
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Just ordered the SHD for studio use as a DAC + monitor controller.

I see a thread on GS about digital vs analog volume control, some claim that digital attenuation can reduce bit depth and signal quality.

A quote from the thread: “Attenuating the signal inside the audio interface's software DOES reduce the bit depth of the outgoing signal. In some very rare cases, the output level trims are controlling an attenuator that comes after the D>A converter inside the interface, but this is not the case with the interface that rds is using.
What rds is doing by turning down the output faders / trims on his audio interface software is reducing the level of the digital signal coming from his DAW software before it goes to the D>A converters, thereby providing a signal of reduced bit depth for those converters.”

The SHD will get full signal from RME interface using the EAS input and going out analog to a stereo monitors and a subwoofer.

The attenuation is basically digital in this case.. the amount of attenuation will be around 40-50 dB.

Is there any reduction in quality when using the SHD this way?

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SHD digital attenuation can reduce bit depth? 5 months 1 week ago #54343

  • entripy
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The SHD has a very large dynamic range so its possible to throw away some bits with poor gain structure and still be left with excellent quality.

However, any digital attenuator will throw away bits. Why do you need 40-50dB attenuation? That is a large amount and suggests poor gain structure, i.e. you are possibly wanting attenuation in the wrong place. 40-50dB of attenuation could easily throw away 8 bits.

The best place for attenuation would be after the SHD, in the analogue domain. I would imagine you could get high quality attenuators with a monitor control system for studio use.

For what its worth my RME drives my SHD which runs around -20dB into a power amplifier, and thats excellent quality.

One significant point is that it only affects your monitoring, not what you actually record.

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SHD digital attenuation can reduce bit depth? 5 months 1 week ago #54349

  • Logix1
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I work with ATC monitors and they are LOUD so for my listening level which is around 65-75dB I need to lower the fader in my audio interface at around 50dB. (I never connect the monitors directly to the RME but I just tested it a few days ago)
I do have a professional monitor controller but I thought the SHD can be both my DAC and a monitor controller, which it can, but the bit depth reduction is not ideal so I will have to test if it noticeable when I will get the SHD in a few days.. thanks.

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SHD digital attenuation can reduce bit depth? 5 months 1 week ago #54352

  • entripy
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If you wish to avoid needing the professional monitor controller one alternative might be inline attenuators. They are analogue, passive, low noise and would allow you to transfer some of the attenuation out of the digital domain. Every 6dB attenuation you transfer to the analogue domain will gain you 1 bit more resolution in the digital domain.

Something like www.hificollective.co.uk/hifi-accessorie...-rca-attenuator.html although I have never used them so cannot vouch for those specific attenuators.
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SHD digital attenuation can reduce bit depth? 5 months 6 days ago #54355

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Isn’t the number of bits simply how far away the noise can be positioned from the signal? While the sampling frequency let’s you reproduce said signal?

So given most digital audio is 16bit and the SHD is 32 bit doesn’t that mean you can reduce the master volume by about 100db before you start loosing any useful bits?

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SHD digital attenuation can reduce bit depth? 5 months 6 days ago #54358

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SHD might have 32 bit convertors but how many useful bits of resolution you get is typically much lower. The spec claims 120dB dynamic range which suggests only 20 bits effective resolution. 40-50dB loss is then quite significant, up to 8 bits, so you could apparently end up with around 12 useful bits, maybe a few more, maybe a few less, but its definitely in the very audible category. And 120dB is only for balanced, you lose an extra bit for unbalanced.

Attenuation loses bits because if you imagine 20 bits, to halve the number you shift one real bit out the least sigificant end and insert a zero at the most significant end. One bit of signal resolution has been lost. Do that 8 times and you are only left with 12 useful bits and 8 zeros.

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SHD digital attenuation can reduce bit depth? 5 months 5 days ago #54366

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you could apparently end up with around 12 useful bits, maybe a few more, maybe a few less, but its definitely in the very audible category.


12 bits is 72 dB dynamic range and the OP as stated is listening at 65-75 dB. I don't think this is "very audible".

Isn’t the number of bits simply how far away the noise can be positioned from the signal?


Yes, that's correct, assuming that the digital attenuation isn't introducing additional components above the noise floor (and there's no reason to think it is).

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